(DUP!) ping issue

lumox

Member
May 29, 2020
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Hi,
I don't know if it is the right place to ask this question because the problem can be due to some thing else completely, I mean not Proxmox, but
you have to start somewhere, right?

Before I deploy a new setup on my real home lab, I gave it a go on my Vmware workstation first:
I created 3 VMs: a GNS3 VM to run a Mikrotik device, a Proxmox VM, and a Windows VM to manage the Proxmox VM. I set up Vlans (100 and 200) in the MK VM, then I set up the linux bridge (vmbr0) as "vlan-aware" in Proxmox . I then created 2 LXC containers in Proxmox, and set/tagged them on VLAN100 and VLAN200 in their network setup respectively. Ok, everything worked as expected.

However, when I run a ping from LXC 200 to 100, it works, but I get a (DUP!) text at the end of every ping line:

Code:
root@debian200:~# ping 192.168.100.200
PING 192.168.100.200 (192.168.100.200) 56(84) bytes of data.
64 bytes from 192.168.100.200: icmp_seq=1 ttl=63 time=126 ms
64 bytes from 192.168.100.200: icmp_seq=1 ttl=63 time=129 ms (DUP!)
64 bytes from 192.168.100.200: icmp_seq=1 ttl=63 time=130 ms (DUP!)
64 bytes from 192.168.100.200: icmp_seq=1 ttl=63 time=130 ms (DUP!)

even when I ping cloudflare:

Code:
root@debian200:~# ping 1.1.1.1       
PING 1.1.1.1 (1.1.1.1) 56(84) bytes of data.
64 bytes from 1.1.1.1: icmp_seq=1 ttl=52 time=86.1 ms
64 bytes from 1.1.1.1: icmp_seq=1 ttl=52 time=86.8 ms (DUP!)
64 bytes from 1.1.1.1: icmp_seq=1 ttl=52 time=102 ms (DUP!)

By looking it up on the Internet I found out that it means "duplicate packet". There could be many reasons for this apparently.
One of them could be the particular VLAN setup, but I have no clue about that honestly. As far as I know, another cause may be the particular virtual environment, since I got the same issue when I ping from the Mikrotik Vm running in GNS3 to a VM, but no problem when I ping cloudflare from the same Mikrotik device.

Could you please help me figure this out?
Thanks
 
Please check your guest mac addresses. Is it possible that multiple guests using the same MAC so that the host is sending each segment to multiple guests?
 
Please check your guest mac addresses. Is it possible that multiple guests using the same MAC so that the host is sending each segment to multiple guests?
I can't check it anymore now because I deleted the entire project, but you may be right anyway. Thanks for the hint. It might come in handy next time.
 

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